Paris Saint-Germain announced the signing of teenage Portugal defender Nuno Mendes from Sporting Lisbon on Tuesday, on a season-long loan with an option to buy.
The 19-year-old, who was part of Sporting's Portuguese title-winning side last season, has won five international caps and was an unused member of Fernando Santos' Euro 2020 squad.
Nuno Mendes completes a bumper transfer window for PSG, who will reportedly pay Sporting a loan fee of seven million euros ($8.3 million) with the option to make the deal permanent for 40 million euros.
"Paris Saint-Germain is delighted to announce the signing of Nuno Mendes," PSG said, confirming the transfer minutes after Tuesday's midnight local time (2200 GMT) deadline.
He had been linked with Premier League clubs including Manchester City earlier in the summer.
The full-back made 35 appearances in all competitions for Sporting in a breakthrough campaign last season.
Spanish international Pablo Sarabia has moved in the opposite direction, joining Sporting on loan until the end of the campaign.
PSG had already signed six-time Ballon d'Or winner Lionel Messi, Italian Euro 2020-winning goalkeeper Gianluigi Donnarumma, former Liverpool midfielder Georginio Wijnaldum and veteran Spain centre-back Sergio Ramos on free transfers in the close-season.
The capital giants, still chasing a maiden Champions League title, also paid Inter Milan a reported 60 million euros for wing-back Achraf Hakimi.